JP2007101527A - Apparatus, method, and program for detecting offset of acceleration sensor and navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately detect zero-gravity offset of acceleration sensors. <P>SOLUTION: When position information PS is acquired from a GPS processing part 4, a speed detection unit 2 highly accurately computes offset acceleration αo by calculations using: actually detected acceleration αGr actually acquired by an acceleration sensor 11; vehicle acceleration αP based on the position information PS; distance Dm; the amount of change Dh in altitude based on atmospheric pressure PR; and gravitational acceleration g, according to the expression (15), and also highly accurately converts acceleration detection signals SA into detection acceleration αG on the basis of a zero-gravity offset value Vzgo converted from the offset acceleration αo. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acceleration sensor offset detection device, an acceleration sensor offset detection method, an acceleration sensor offset detection program, and a navigation device, and is suitable for application to, for example, a navigation device mounted on a vehicle.

  Conventionally, in a navigation device, a current position is calculated based on a GPS signal mounted on a moving vehicle or the like and transmitted from a GPS (Global Positioning System) satellite, and the position and traveling direction of the vehicle are indicated on a map screen. What has been made is widely spread.

  In such a navigation device, the speed and direction of travel of the vehicle are calculated using an acceleration sensor that detects acceleration in the direction of travel of the vehicle, a gyro sensor (yaw rate sensor) that detects the rotational angular speed of the vehicle in the horizontal direction, and the like. By doing so, the current position of the vehicle can be estimated even when GPS signals cannot be received, such as behind a building or in a tunnel.

  However, this acceleration sensor has a problem in that the output voltage when the acceleration is not detected, that is, the so-called zero gravity offset fluctuates due to the temperature characteristics due to the influence of the ambient temperature, the heat generation of the navigation device itself, and the like.

Therefore, some navigation devices calculate the amount of change in altitude (difference in altitude) by using the direction of gravity acceleration component included in the acceleration sensor detection value when the vehicle travels on an inclined surface, and store it in map information. It has been proposed to calculate a zero gravity offset (acceleration error) by comparing with a known altitude change amount based on altitude data or the like (for example, see Patent Document 1).
JP 2004-233306 A

  However, in such a navigation device, for example, when the exact amount of change in altitude is unknown, such as when the vehicle is traveling in a place where altitude data is not included in the map information, the zero gravity offset cannot be calculated. There was a problem.

  The present invention has been made in consideration of the above points. An offset detection device for an acceleration sensor, an offset detection method for an acceleration sensor, an offset detection program for an acceleration sensor, and a moving body can detect the zero gravity offset of the acceleration sensor with high accuracy. It is intended to propose a navigation device capable of presenting highly accurate information regarding the position of each other.

  In order to solve such a problem, in the offset detection apparatus for the acceleration sensor, the offset detection method for the acceleration sensor, and the offset detection program for the acceleration sensor according to the present invention, the offset variation is added to the acceleration in the traveling direction of the predetermined moving body. The actual detected acceleration corresponding to the result is obtained by the acceleration sensor, the estimated acceleration that the acceleration sensor should originally detect is calculated, and the actual detected acceleration is calculated according to the characteristics of the acceleration sensor based on the difference between the actual detected acceleration and the detected acceleration. The offset variation where the detected acceleration fluctuated from the detected acceleration was calculated.

  As a result, the offset fluctuation can be calculated based only on the difference between the actual detected acceleration and the scheduled detection acceleration, and a highly accurate acceleration reflecting the offset fluctuation can be obtained.

  In the navigation apparatus of the present invention, a current position calculation means for receiving a positioning signal from a predetermined satellite positioning system and calculating a current position of the predetermined moving body, and an offset to an acceleration in the traveling direction of the predetermined moving body An acceleration sensor that obtains an actual detection acceleration corresponding to the result of adding the variation, a detection scheduled acceleration calculation means that calculates a detection scheduled acceleration that the acceleration sensor should originally detect correctly, an actual detection acceleration and a detection scheduled acceleration; On the basis of the difference between the offset calculation means for calculating the offset fluctuation amount in which the actual detected acceleration fluctuates from the acceleration to be detected according to the characteristics of the acceleration sensor, and the acceleration is calculated using the offset fluctuation amount calculated by the offset calculation means, Information presenting means for presenting information relating to the position of the moving body based on the speed of the moving body calculated using the acceleration; It was provided.

  As a result, it is possible to calculate the offset fluctuation based only on the difference between the actual detected acceleration and the scheduled detection acceleration, and obtain a high-accuracy acceleration reflecting the offset fluctuation to obtain a high-accuracy regarding the position of the moving object. Information can be presented.

  According to the present invention, it is possible to calculate the offset fluctuation based only on the difference between the actual detected acceleration and the scheduled detection acceleration, it is possible to obtain a highly accurate actual detected acceleration reflecting the offset fluctuation, Thus, an acceleration sensor offset detection device, an acceleration sensor offset detection method, and an acceleration sensor offset detection program that can detect the zero gravity offset of the acceleration sensor with high accuracy can be realized.

  Further, according to the present invention, it is possible to calculate the offset fluctuation amount based only on the difference between the actual detected acceleration and the scheduled detection acceleration, and by reflecting the offset fluctuation amount, highly accurate information on the position of the moving object. Can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of Navigation Device In FIG. 1, a navigation device 1 is mounted on a vehicle 100 (FIG. 2) as a moving body, and is a GPS (Global Positioning System) processing unit. 4 calculates the current position of the vehicle 100 on the basis of the GPS signal received from the GPS satellite, and the navigation unit 3 superimposes a mark or the like indicating the current position of the vehicle 100 on the predetermined map data. This is generated and sent to the display unit 5 to display a display screen, whereby the user can visually recognize the position of the vehicle 100 on the map.

  The GPS processing unit 4 receives GPS signals from a plurality of GPS satellites (not shown) via the GPS antenna 6, and generates a position signal PS by performing a predetermined position calculation process based on the GPS signals. This is supplied to the arithmetic processing block 10 of the speed detection unit 2 and the navigation unit 3.

  The speed detection unit 2 is configured around an arithmetic processing block 10, and includes an acceleration sensor 11 that detects acceleration acting in the traveling direction of the vehicle 100, an atmospheric pressure sensor 12 that detects ambient atmospheric pressure, and a vertical direction of the vehicle 100. A yaw rate sensor 13 that detects a rotational angular velocity around the direction is connected to the arithmetic processing block 10.

  The acceleration sensor 11 generates an acceleration detection signal SA whose potential varies in the range of 0 [V] to 5 [V] according to the acceleration acting in the traveling direction of the vehicle 100, and supplies this to the arithmetic processing block 10. . Incidentally, the acceleration sensor 11 is configured such that the potential of the acceleration detection signal SA is 2.5 [V] when no acceleration is applied in the traveling direction of the vehicle 100 (hereinafter, acceleration detection at this time). The potential of the signal SA is called zero gravity offset value Vzgo).

  The atmospheric pressure sensor 12 generates an atmospheric pressure detection signal SR whose potential varies in a predetermined range according to the ambient atmospheric pressure, and supplies this to the arithmetic processing block 10.

  The yaw rate sensor 13 detects an angular velocity φ around the vertical direction of the vehicle 100 (that is, around the yaw rotation axis), and supplies this to the arithmetic processing block 10.

  The arithmetic processing block 10 applies the acceleration detection signal SA supplied from the acceleration sensor 11 in the traveling direction of the vehicle 100 with reference to the conversion reference potential Vsc (that is, 2.5 [V]) that is the same as the zero gravity offset value Vzgo. After converting the atmospheric pressure detection signal SR supplied from the atmospheric pressure sensor 12 into an atmospheric pressure value PR representing the ambient atmospheric pressure, the position signal PS supplied from the GPS processing unit 4 and the detected acceleration αG The speed V of the vehicle 100 is calculated based on the pressure value PR and the atmospheric pressure value PR, and this is sent to the navigation unit 3.

  The arithmetic processing block 10 has a CPU (Central Processing Unit) configuration (not shown), and reads and executes various application programs such as a speed calculation program from a ROM (Read Only Memory) (not shown), thereby executing the vehicle 100 in a predetermined measurement period. Travel distance calculation unit 13 for calculating the travel distance of the vehicle, the altitude difference calculation unit 14 for calculating the altitude difference of the vehicle 100 in the measurement period based on the atmospheric pressure PR (described later in detail), and the vehicle 100 being stopped or traveling Is included in the detected acceleration αG supplied from the acceleration sensor 11, the stop determination unit 15 that determines whether the vehicle is a vehicle, the speed calculation unit 16 that calculates the speed V of the vehicle 100 (described in detail later), and the acceleration sensor 11. Each processing function such as an offset calculation unit 17 for calculating a gravity offset ZGO (details will be described later) is realized. It has been made to so that.

  The arithmetic processing block 10 stores the calculated speed V, zero gravity offset ZGO, and the like in the storage unit 18 formed of a nonvolatile memory, and reads it out as necessary.

  Incidentally, the navigation device 1 is configured not to use a pulsed vehicle speed pulse signal that is generated in the vehicle 100 and whose period changes in accordance with the speed of the vehicle 100, and when the navigation device 1 is attached to the vehicle 100. Wiring processing can be simplified.

  As described above, the speed detection unit 2 of the navigation device 1 calculates the speed V of the vehicle 100 and calculates the zero gravity offset ZGO included in the detected acceleration αG supplied from the acceleration sensor 11. .

(1-2) Basic Principle of the Present Invention Next, the basic principle of the present invention will be described. Here, as shown in FIG. 2A, it is assumed that the vehicle 100 is traveling on a slope SL having a gradient angle θ with respect to the horizontal plane HZ. In this case, the detected acceleration αG detected by the acceleration sensor 11 (FIG. 1) includes an original acceleration resulting from the movement of the vehicle 100 (hereinafter referred to as a vehicle acceleration αP) and a gravity acting on the vehicle 100. This corresponds to a value obtained by adding a traveling direction component of acceleration g (hereinafter referred to as a gravitational acceleration component gf). That is, the gravitational acceleration component gf is expressed by the following equation by the difference between the detected acceleration αG and the vehicle acceleration αP.

It can be calculated as follows.

  The speed detection unit 2 (FIG. 1) of the navigation device 1 can calculate the vehicle acceleration αP after calculating the distance and speed based on a plurality of position signals PS at a plurality of times.

  By the way, as shown in FIGS. 2B and 2C, the vehicle 100 is inclined SL during a measurement time mt (for example, about 1 second) from a certain time t0 as the measurement start time to a time t1 as the measurement end time. The ratio (that is, sin θ) between the distance Dm that travels through the vehicle and the altitude change amount Dh of the vehicle 100 at the measurement time mt is equal to the ratio between the gravitational acceleration component gf and the gravitational acceleration g (that is, sin θ). Therefore, the following formula

The relationship is established.

  By the way, the distance Dm described above is expressed by the following formula using the speed V0 of the vehicle 100 and the vehicle acceleration αP at time t0 according to a general formula using the speed and acceleration related to the distance.

It can be expressed as Here, if the equation (2) is modified and the equations (1) and (3) are substituted,

become that way.

(1-2-1) Speed Calculation By the way, the speed detection unit 2 (FIG. 1) of the navigation device 1 cannot receive a GPS signal from a GPS satellite by the GPS antenna 6 such as behind a building or in a tunnel. Since the navigation unit 3 cannot calculate the current position of the vehicle 100 based on the position signal PS from the GPS processing unit 4, the current position is estimated based on the speed V of the vehicle 100 and the angular velocity φ in the horizontal direction, A map screen based on this is displayed on the display unit 5.

  However, since the speed detection unit 2 (FIG. 1) of the navigation device 1 cannot receive the GPS signal at the GPS antenna 6, the speed detection unit 2 (FIG. 1) simply calculates the speed V based on the temporal change of the position signal PS supplied from the GPS processing unit 4. Cannot be used.

  Therefore, the speed calculation unit 16 of the speed detection unit 2 calculates the speed V1 at time t1 based on the speed V0 at time t0 without using the position signal PS. Hereinafter, the principle will be described.

  First, when the above equation (4) is arranged for the vehicle acceleration αP, the following equation:

Is obtained. Here, the speed V1 at time t1 follows the general physics formula for the speed V and is

The relationship is established. This indicates that the speed V1 can be calculated based on the speed V0. Here, by substituting equation (5) into equation (6),

Can be obtained.

  That is, if the speed detection unit 2 can obtain the altitude change amount Dh, the speed V1 at the time t1 is obtained by using the detected acceleration αG, the measurement time mt, the speed V0 at the time t0, the gravitational acceleration g, and the altitude change amount Dh. Can be calculated.

  In this case, the speed detection unit 2 directly calculates the formula (7), but the formula (7) is obtained by substituting the formula (5) into the formula (6). Therefore, the speed detection unit 2 indirectly obtains the vehicle acceleration αP, and uses this to obtain the speed V1 at time t1 from the speed V0 at time t0.

(1-2-2) Determination of Stopped State As shown in the equation (6), the vehicle speed detection unit 2 uses the speed V0 at time t0 (that is, immediately before) and uses the speed V0 at time t1 (that is, current). Since V1 is calculated, if the speed V0 is incorrect, the speed V1 also becomes an incorrect value. For this reason, the vehicle speed detection unit 2 needs to reliably detect the initial speed V of the vehicle 100, that is, the speed V in a stopped state as “zero”.

  In general, when the vehicle 100 is traveling, the speed V constantly fluctuates according to the shape of the road, traffic conditions, and the like, and therefore, the possibility that the speed V continues to be a constant value is extremely low. The value of the speed V has a certain degree of variation. On the contrary, when the vehicle 100 is stopped, the speed V does not fluctuate from zero and becomes a constant value, and even if a detection error is taken into consideration, the variation in the speed V falls within a predetermined range.

  Therefore, the vehicle speed detection unit 2 calculates the variance Vvar of the speed V in a predetermined time range (for example, 5 seconds) by the stop determination unit 15, and the vehicle 100 is stopped if the variance Vvar is within the predetermined range. And the speed V at this time is corrected to zero.

  As a result, the vehicle speed detection unit 2 can correctly determine whether the vehicle 100 is in the running state or the stopped state. If the vehicle 100 is in the stopped state, the vehicle speed detection unit 2 corrects the speed V to zero so that the subsequent speed V Can be calculated correctly.

(1-2-3) Calculation of Altitude Change Amount Next, an altitude change amount Dh calculation process in the speed detection unit 2 (FIG. 1) will be described. The speed detection unit 2 calculates the altitude change amount Dh by using the distance Dm, the gravitational acceleration component gf (that is, the detected acceleration αG−the vehicle acceleration αP) and the gravitational acceleration g, as shown in the above-described equation (2). be able to.

  Here, when the GPS signal can be received by the GPS antenna 6, the speed detection unit 2 can calculate the distance Dm that the vehicle 100 has moved within the measurement time mt in the movement distance calculation unit 13, and therefore, based on the distance Dm. In addition, the speed V of the vehicle 100 can be calculated, and the vehicle acceleration αP can be calculated based on this.

  However, the speed detection unit 2 cannot calculate the distance Dm and the vehicle acceleration αP when the GPS antenna 6 cannot receive the GPS signal from the GPS satellite and the GPS processing unit 4 cannot generate the position information PS. ) The altitude change amount Dh cannot be calculated from the relationship of the equation.

  Therefore, the speed detection unit 2 uses the fact that there is generally a correspondence between the atmospheric pressure PR and the altitude h, and if the GPS processing unit 4 cannot generate the position information PS, the atmospheric pressure PR acquired from the atmospheric pressure sensor 12 is used as the altitude h. It is made to convert to.

  In practice, the speed detection unit 2 stores a barometric altitude correspondence table TBL in which correspondences between general barometric pressures and altitudes are preliminarily stored in the storage unit 18, and the atmospheric pressure PR0 at time t0 and the atmospheric pressure PR1 at time t1 are stored. Based on the atmospheric pressure altitude correspondence table TBL, altitudes h0 and h1 corresponding to the atmospheric pressures PR0 and PR1 are read out.

  Subsequently, the speed detection unit 2 calculates an altitude change amount Dh, which is a difference between the altitude h0 of the vehicle 100 at time t0 and the altitude h1 of the vehicle 100 at time t1, using the following equation.

According to the calculation.

  Here, with regard to the altitude change amount Dh, the range that can be actually taken (hereinafter referred to as the altitude change) will be taken into consideration in consideration of the gradient range on a general road, the running performance of the vehicle 100 (that is, the travel distance per unit time), and the like. It is considered that there are upper and lower limit values (referred to as ranges).

  On the other hand, when the vehicle 100 actually travels on the road, for example, when the window of the vehicle 100 is opened or closed, when entering the tunnel, or when passing the adjacent lane, etc. The atmospheric pressure may change (hereinafter, these factors are referred to as non-altitude factors).

  In such a case, the speed detection unit 2 will calculate an incorrect altitude h based on the atmospheric pressure PR affected by the non-altitude factor, and the altitude change amount Dh also becomes an incorrect value. End up.

  By the way, when under the influence of such a non-altitude factor, it is considered that the atmospheric pressure PR in the passenger compartment changes abruptly as compared with the case where it is caused only by the altitude. That is, the altitude change amount Dh at this time is likely to be out of the altitude change range.

  Therefore, when the altitude change amount Dh calculated by the equation (8) is out of the altitude change range, the speed detection unit 2 considers that the altitude change amount Dh is affected, and corrects the altitude change amount Dh. Has been made.

  Specifically, the speed detection unit 2 defines the maximum value of the gradient angle θ (FIG. 2) that can actually be taken as the maximum gradient angle θmax (for example, 0.05π [rad], etc.), and calculates the calculated altitude change amount Dh and immediately before Using the following speed V0

Whether or not is satisfied is determined. Incidentally, the right side of the equation (9) represents the “maximum altitude difference that can be assumed from the immediately preceding speed V0” as a whole by multiplying the immediately preceding speed V0 by sin (θmax).

  Here, when the equation (9) is established, the speed detection unit 2 considers that the altitude change amount Dh calculated by the equation (8) is not affected by the non-altitude factor, and is a correct value. The following processing is performed without performing it.

  On the other hand, when the equation (9) is not satisfied, the speed detection unit 2 considers that the altitude change amount Dh calculated by the equation (8) is affected by the non-altitude factor,

The corrected altitude change amount Dhc is calculated as follows. Thereafter, the speed detection unit 2 sets the corrected height change amount Dhc as a new height change amount Dh and performs the subsequent processing.

  In this case, since the speed calculation unit 2 cannot calculate the correct altitude change amount Dh from the atmospheric pressure PR in the passenger compartment, the corrected altitude change amount Dhc is calculated as the maximum possible altitude change amount Dh as the next best measure. This is used as the altitude change amount Dh.

  The atmospheric pressure generally varies depending on the altitude, and even at the same altitude, it varies slowly due to the influence of weather such as low and high atmospheric pressure. However, the measurement time mt (about 1 second), which is the time difference when the speed detection unit 2 detects the atmospheric pressures PR0 and PR1, is sufficiently shorter than the time during which significant atmospheric pressure fluctuations occur due to the influence of the weather. It can be considered that the altitude change amount Dh as a relative difference has no influence on the atmospheric pressure due to weather or the like.

  Therefore, the speed detection unit 2 can obtain the highly reliable altitude change amount Dh from the atmospheric pressure altitude correspondence table TBL and the equation (8), and apply the altitude change amount Dh thus calculated to the equation (7). can do.

  In this case, since the speed detection unit 2 cannot calculate the accurate vehicle acceleration αP, the traveling direction component gf included in the detected acceleration αG cannot be directly calculated by the relationship of the expression (1). Since the traveling direction component gf can be canceled by the altitude change amount Dh using the relationship shown in the expression (2), as a result, the velocity V can be accurately calculated by the expression (7) regardless of the traveling direction component gf. Can be calculated.

(1-2-4) Calculation of Zero Gravity Offset By the way, the acceleration sensor 11 (FIG. 1) is accelerated in the traveling direction of the vehicle 100 as when the vehicle 100 is stopped on the horizontal plane HZ (FIG. 2). When not acting, as shown in FIG. 3A, the potential of the acceleration detection signal SA output from the acceleration sensor 11, that is, the zero gravity offset value Vzgo is 2.5 [V].

  However, due to the characteristics of the acceleration sensor 11, the zero gravity offset value Vzgo fluctuates from 2.5 [V] to 2.6 [V], 2.7 [V], etc. due to the influence of the ambient temperature change or the like. (Indicated by broken lines in the figure).

  At this time, the speed detection unit 2 detects from the acceleration detection signal SA in the arithmetic processing block 10 as shown in FIG. 3B, although the zero gravity offset value Vzgo varies from 2.5 [V]. If the conversion reference potential Vsc when converting to the acceleration αG is left as the zero gravity offset value Vzgo (that is, 2.5 [V]) before the change, the conversion reference potential Vsc is converted to an erroneous detection acceleration αG. The speed V calculated by the equation (7) also becomes an incorrect value.

  For this reason, the speed detection unit 2 detects the zero gravity offset value Vzgo after the fluctuation, and then updates the conversion reference potential Vsc based on the zero gravity offset value Vzgo, thereby detecting the acceleration detection signal SA from the acceleration sensor 11. Is preferably converted into a correct detected acceleration αG.

  Here, the actual detected acceleration αG (hereinafter referred to as the actual detected acceleration αGr) obtained by converting the acceleration detection signal SA output from the acceleration sensor 11 is detected acceleration αG (hereinafter referred to as the actual detected acceleration αGr). , This is called the scheduled detection acceleration αGi) and the acceleration corresponding to the variation of the zero gravity offset value Vzgo (hereinafter referred to as the offset acceleration αo).

The following equation is established by transforming this relationship:

Is obtained. That is, it can be seen that the offset acceleration αo can be calculated as a difference between the actual detected acceleration αGr and the scheduled detection acceleration αGi.

  Here, for the scheduled acceleration αGi, since the relationship of the above-described equation (1) can be applied, the equation (12) is expressed by the following equation:

Can be replaced as follows.

  Moreover, the following formula can be obtained by modifying the formula (2).

Can be obtained.

  Here, the speed detection unit 2 can calculate the altitude change amount Dh based on the atmospheric pressure PR acquired from the atmospheric pressure sensor 12 (FIG. 1) as shown in the equation (8), and the distance at the measurement time mt. As for Dm and vehicle acceleration αP, as described above, when a GPS signal can be received by the GPS antenna 6 (FIG. 1), the movement distance calculation unit 13 obtains the distance Dm based on the position information PS, and further uses this. Thus, the vehicle acceleration αP can be calculated.

  In other words, when the GPS signal can be received by the GPS antenna 6, the speed detection unit 2 can be obtained by applying the equation (14) to the equation (13) described above.

By substituting the actual detected acceleration αGr, the vehicle acceleration αP, the altitude change Dh, the distance Dm, and the gravitational acceleration g, the offset acceleration αo can be calculated.

  At this time, the speed detection unit 2 can obtain the latest zero gravity offset value Vzgo by converting the offset acceleration αo, and the converted reference potential Vsc stored in the storage unit 18 (FIG. 1) is used as the zero gravity. By updating to the same value as the offset value Vzgo, the acceleration detection signal SA from the acceleration sensor 11 can be converted into the correct detected acceleration αG in consideration of the variation of the zero gravity offset value Vzgo in the arithmetic processing block 10.

  Incidentally, when the speed detection unit 2 can receive the GPS signal by the GPS antenna 6 and acquire the position information PS from the GPS processing unit 4, the speed detection unit 2 calculates the offset acceleration αo as needed according to the equation (15) and updates the conversion reference potential Vsc as needed. When the GPS signal cannot be received, the velocity V is calculated according to the equation (7) using the correct detected acceleration αG based on the latest converted reference potential Vsc, that is, considering the variation of the zero gravity offset value Vzgo. Has been made.

(1-3) Speed Output Processing Next, the speed output processing procedure when the speed detection unit 2 calculates the speed V of the vehicle 100 and outputs it to the navigation unit 3 will be described using the flowchart of FIG.

  When the navigation device 1 is turned on, the arithmetic processing block 10 of the speed detection unit 2 starts the speed output processing procedure RT1 and proceeds to step SP1. In step SP1, the arithmetic processing block 10 calculates the variance Vvar at the vehicle speed V calculated in the past 15 seconds in order to determine whether or not the vehicle 100 is in the stopped state by the stop determination unit 15, and proceeds to the next step SP2. .

  In step SP2, the arithmetic processing block 10 determines whether or not the variance Vvar of the vehicle speed V calculated in step SP1 by the stop determination unit 15 is below a predetermined threshold value. If a positive result is obtained here, this indicates that the possibility that the vehicle 100 is in a stopped state is very high because the variance Vvar is relatively small, and at this time, the arithmetic processing block 10 is Move to next Step SP3.

  In step SP3, the arithmetic processing block 10 corrects the immediately preceding speed V0 stored in the storage unit 18 to zero, and proceeds to the next step SP4.

  On the other hand, if a negative result is obtained in step SP2, this indicates that there is a high possibility that the vehicle 100 is in a traveling state because the variance Vvar of the vehicle speed V is large to some extent. The process proceeds to the next step SP4 without particularly correcting the speed V0.

  In step SP4, the arithmetic processing block 10 determines whether or not the position information PS is acquired from the GPS processing unit 4. If an affirmative result is obtained here, this indicates that the speed of the vehicle 100 can be calculated based on the position information PS acquired from the GPS processing unit 4, and at this time, the arithmetic processing block 10 proceeds to the next subroutine SRT1. Move.

  In the subroutine SRT1, the arithmetic processing block 10 updates the conversion reference potential Vsc by calculating the offset acceleration αo according to the above-described equation (15) by the offset calculation unit 17 (details will be described later), and proceeds to the next step SP5.

  Incidentally, the arithmetic processing block 10 is configured to calculate the current velocity V based on the position information PS in the process of calculating the offset acceleration αo in the subroutine SRT1.

  On the other hand, if a negative result is obtained in step SP4, this means that the position information PS cannot be acquired from the GPS processing unit 4, and therefore it is necessary to calculate the velocity V without using the position information PS. When this is the case, the arithmetic processing block 10 proceeds to the next subroutine SRT2.

  In the subroutine SRT2, the arithmetic processing block 10 calculates the current speed V (speed V1) according to the above-described equation (7) by the speed calculation unit 16 (details will be described later), and proceeds to the next step SP5.

  In step SP5, the arithmetic processing block 10 sends the speed V to the navigation unit 3, and proceeds to the next step SP6.

  In step SP6, the arithmetic processing block 10 waits until the measurement time mt elapses, and then returns to step SP1 again to repeat a series of processes.

(1-3-1) Offset Acceleration Calculation Processing Next, offset acceleration calculation processing when the calculation processing block 10 calculates the offset acceleration αo by the offset calculation unit 17 will be described with reference to the flowchart of FIG. Here, the current time is set as time t1, and the time before the measurement time mt from the time t1 is set as time t0.

  The arithmetic processing block 10 starts the offset acceleration calculation subroutine SRT1 shown in FIG. 5 in response to a call from the speed output processing procedure RT1 (FIG. 4), and proceeds to step SP11. In step SP11, the arithmetic processing block 10 acquires the detected acceleration αG1 at the current time t1 from the acceleration sensor 11, acquires the atmospheric pressure PR1 from the atmospheric pressure sensor 12, and further acquires the position information PS1 from the GPS processing unit 4, The process proceeds to step SP12.

  In step SP12, the arithmetic processing block 10 reads the detected acceleration αG0, the atmospheric pressure PR0, and the position information PS0 at time t0 stored in the storage unit 18 in advance, and proceeds to the next step SP13.

  In step SP13, the arithmetic processing block 10 reads the altitudes h0 and h1 corresponding to the atmospheric pressures PR0 and PR1 using the atmospheric pressure altitude correspondence table TBL stored in the storage unit 18, and calculates the altitude change amount Dh according to the equation (8). Then, the process proceeds to the next altitude change correction subroutine SRT3 (FIG. 6).

  The arithmetic processing block 10 proceeds to step SP51 and determines whether or not the altitude change amount Dh satisfies the expression (9), that is, whether or not the altitude change amount Dh is affected by a non-altitude factor. If a positive result is obtained here, this indicates that there is a high possibility that the altitude change amount Dh is not affected by non-altitude factors, and it is not necessary to correct the altitude change amount Dh. Then, the arithmetic processing block 10 moves to step SP54, ends the subroutine SRT3, and returns to the original subroutine SRT1 (FIG. 5).

  On the other hand, if a negative result is obtained in step SP51, this indicates that there is a high possibility that the altitude change amount Dh is affected by a non-altitude factor, and that the altitude change amount Dh should be corrected. At this time, the arithmetic processing block 10 proceeds to the next step SP52.

  In step SP52, the arithmetic processing block 10 calculates the corrected altitude change amount Dhc according to the equation (10), moves to the next step SP53, and sets the corrected altitude change amount Dhc as a new altitude change amount Dh, and moves to the next step SP54. .

  In step SP54, the arithmetic processing block 10 ends the routine RT3, returns to the original subroutine SRT1 (FIG. 5), and proceeds to the next step SP14.

  In step SP14, the arithmetic processing block 10 calculates the distance Dm that the vehicle 100 has moved in the measurement time mt based on the position information PS0 and PS1 by the distance calculation unit 13, and further calculates the speed V based on the distance Dm. From the above, the vehicle acceleration αP is calculated, and the process proceeds to the next step SP15.

  In step SP15, the arithmetic processing block 10 calculates the offset acceleration αo using the actual detected acceleration αGr (in this case, the detected acceleration αG0), the vehicle acceleration αP, the altitude change Dh, the distance Dm, and the gravitational acceleration g according to the equation (15). Then, the process proceeds to the next step SP16.

  In step SP16, the arithmetic processing block 10 calculates the zero gravity offset value Vzgo by converting the offset acceleration αo into a potential, and the conversion reference potential Vsc stored in the storage unit 18 is the same as the zero gravity offset value Vzgo. The value is updated to the next step SP17.

  In step SP17, the arithmetic processing block 10 stores the detected acceleration αG1, the atmospheric pressure PR1 and the position information PS1 at the current time t1 in the storage unit 18 in order to calculate the next offset acceleration αo, and moves to the next step SP18. The offset acceleration calculation subroutine SRT1 is terminated, and the process returns to the original speed output processing procedure RT1 (FIG. 4).

(1-3-2) Speed Calculation Processing Next, the speed calculation processing when the speed calculation unit 16 calculates the speed V when the arithmetic processing block 10 cannot acquire the position information PS from the GPS processing unit 4 will be described with reference to FIG. It demonstrates using the flowchart of these. Here, the current time is set as time t1, and the time before the measurement time mt is set as time t0.

  In response to the call from the speed output processing procedure RT1 (FIG. 4), the arithmetic processing block 10 starts the speed calculation subroutine SRT2 shown in FIG. 7 and proceeds to step SP21. In step SP21, the arithmetic processing block 10 acquires the detected acceleration αG1 at the current time t1 from the acceleration sensor 11 and the atmospheric pressure PR1 from the atmospheric pressure sensor 12, and proceeds to the next step SP22.

  In step SP22, the arithmetic processing block 10 reads the detected acceleration αG0, the atmospheric pressure PR0, and the speed V0 at time t0 stored in advance in the storage unit 18, and proceeds to the next step SP23.

  In step SP23, the arithmetic processing block 10 uses the atmospheric pressure altitude correspondence table TBL stored in the storage unit 18 and the altitude h0 corresponding to the atmospheric pressures PR0 and PR1 as in step SP13 of the offset acceleration calculation subroutine SRT1 (FIG. 4). h1 is read out, the altitude change amount Dh is calculated according to the equation (8), and the routine proceeds to subroutine SRT3 (FIG. 6).

  In the subroutine SRT3, as in the subroutine SRT1, the arithmetic processing block 10 determines whether or not the altitude change amount Dh is affected by a non-altitude factor using the equation (9). After correcting the altitude change amount Dh by calculating the corrected altitude change amount Dhc according to the equation (10) and setting it as a new altitude change amount Dh, the process returns to the original subroutine SRT2 (FIG. 7) and proceeds to the next step SP24. Move.

  In step SP24, the arithmetic processing block 10 calculates the velocity V1 at the current time t1 using the detected acceleration αG0, the velocity V0 at the time t0, the altitude change Dh, the measurement time mt, and the gravitational acceleration g according to the equation (7). Control goes to the next step SP25.

  In step SP25, the arithmetic processing block 10 stores the detected acceleration αG1, the atmospheric pressure PR1 and the speed V1 at the current time t1 in the storage unit 18 for the next time of calculating the speed V, and moves to the next step SP26 to move to this speed. The calculation subroutine SRT2 is terminated, and the process returns to the original speed output processing procedure RT1 (FIG. 4).

(1-4) Operation and Effect In the above configuration, when the speed detection unit 2 can receive a GPS signal by the GPS antenna 6, the actual detection acceleration αGr, the vehicle acceleration αP, the altitude change amount Dh, and the distance are expressed by the equation (15). By substituting Dm and gravitational acceleration g, the offset acceleration αo is calculated.

  Therefore, if the speed detection unit 2 can acquire the position information PS from the GPS processing unit 4, the actual detection acceleration αGr actually obtained from the acceleration sensor 11, the vehicle acceleration αP, the distance Dm, and the atmospheric pressure PR based on the position information PS. Using the altitude change amount Dh and the gravitational acceleration g based on the offset acceleration αo can be calculated with high accuracy.

  In this case, although the speed detection unit 2 cannot directly obtain the value of the scheduled detection acceleration αgi, the vehicle based on the actual detection acceleration αGr actually obtained from the acceleration sensor 11 and the position information PS according to the equation (15). Based on the difference from the planned detection acceleration αgi obtained based on the acceleration αP, the altitude change Dh, the distance Dm, and the gravitational acceleration g (that is, the term in the parentheses in the equation (15)), the offset acceleration αo is highly accurate. Can be calculated.

  In particular, since the speed detection unit 2 calculates the altitude change amount Dh based on the atmospheric pressure PR, it is not necessary to obtain the altitude change amount Dh in advance using map information or the like, and it can be detected regardless of the presence or absence of altitude data. The scheduled acceleration αgi can be calculated, and thereby the offset acceleration αo can be calculated.

  Moreover, since the speed detection unit 2 can convert the atmospheric pressure PR into the altitude h using the atmospheric pressure altitude correspondence table TBL stored in the storage unit 18 in advance, the altitude h according to a predetermined calculation process using the atmospheric pressure PR. Compared with the case of calculating, the amount of calculation processing can be reduced.

  Further, when it is determined that the altitude change amount Dh is influenced by the non-altitude factor based on the determination using the equation (9), the speed detection unit 2 calculates the corrected altitude change amount Dhc according to the equation (10). . As a result, the speed detection unit 2 corrects the altitude change amount Dh, which is likely to be a large erroneous value due to a non-altitude factor only by the equation (8), to the corrected altitude change amount Dhc, which is the next best value. Therefore, the range of error in the value of the altitude change amount Dh and the value of the velocity V calculated using the altitude change amount Dh can be reduced.

  Furthermore, since the speed detection unit 2 can calculate the offset acceleration αo while the vehicle is traveling, the trouble of “detecting the offset acceleration in a stationary state in a horizontal place”, which was necessary in the conventional method, is unnecessary. Thus, the calculation conditions for the offset acceleration αo can be greatly relaxed.

  Thereby, the speed detection unit 2 can obtain the latest zero gravity offset value Vzgo by converting the offset acceleration αo, and is affected by the temperature characteristics of the acceleration sensor 11 based on the zero gravity offset value Vzgo. The acceleration detection signal SA can be converted into the detected acceleration αG with high accuracy.

  In addition, since the speed detection unit 2 can calculate the offset acceleration αo every measurement time mt, the offset acceleration αo that may change as the temperature of the navigation device 1 rises as time elapses is updated as needed. And can always be converted into a highly accurate detected acceleration αg.

  According to the above configuration, when the speed detection unit 2 can acquire the position information PS from the GPS processing unit 4, the actual detection acceleration αGr actually obtained from the acceleration sensor 11 and the position information PS according to the equation (15). The offset acceleration αo can be calculated with high accuracy by using the vehicle acceleration αP based on the above, the distance Dm, the altitude change amount Dh based on the atmospheric pressure PR, and the gravitational acceleration g, and the zero gravity offset value obtained by converting the offset acceleration αo Based on Vzgo, the acceleration detection signal SA can be converted to the detected acceleration αG with high accuracy.

(2) Second Embodiment (2-1) Configuration of Navigation Device As shown in FIG. 8 in which parts corresponding to those in FIG. 1 are given the same reference numerals, the navigation device 20 in the second embodiment is The navigation apparatus 1 has the same configuration as that of the navigation apparatus 1 (FIG. 1) except that a speed detection unit 21 is provided instead of the detection unit 2.

  The speed detection unit 21 has an arithmetic processing block 22 instead of the arithmetic processing block 10 in the speed detection unit 2 (FIG. 1). In addition to the configuration of the arithmetic processing block 10, the arithmetic processing block 22 is provided with an angular velocity correction unit 23 that performs a correction process of the angular velocity φ supplied from the yaw rate sensor 13.

  As shown in FIG. 9A corresponding to FIG. 2A, it is assumed that the vehicle 100 is traveling on a slope SL having a gradient angle θ with respect to the horizontal plane HZ in the traveling direction FW.

  Here, the angular velocity φ detected by the yaw rate sensor 13 represents a rotational angular velocity around the virtual yaw rotation axis YA of the vehicle 100 on the slope SL, as shown in FIG. 9B.

  In this case, since the vehicle 100 is traveling on the slope SL, the angular velocity φ detected by the yaw rate sensor 13 is a value obtained by multiplying the actual rotational angular velocity of the vehicle 100 by cos θ.

  Therefore, the angular velocity correction unit 23 (FIG. 8) of the arithmetic processing block 22 is obtained based on the altitude change Dh calculated according to the equation (8) and the velocity V calculated according to the equation (7) as advance preparation. Using the movement distance Dm, as shown in FIG.

Sin θ is calculated using the relationship of the following, and using this, the following equation based on the properties of a general trigonometric function:

To calculate cos θ.

  Next, the angular velocity correction unit 23 uses the cos θ to

9B, a corrected angular velocity φc as shown in FIG. 9B is calculated and sent to the navigation unit 3 together with the velocity V calculated based on the equation (7).

  In response to this, the navigation unit 3 cannot receive the GPS signal by the GPS antenna 6 and cannot acquire the position information PS from the GPS processing unit 4, and based on the GPS signal speed V and the corrected angular speed φc, So-called dead reckoning (dead reckoning) is performed to calculate the current estimated position of the vehicle 100 from the position.

  At this time, even if the vehicle 100 is traveling on the slope SL and the angular velocity φ detected by the yaw rate sensor 13 is different from the original angular velocity of the vehicle 100, the navigation unit 3 is not the angular velocity φ but the slope of the slope SL. By using the corrected angular velocity φc corrected according to the angle θ, the estimated position of the vehicle 100 can be calculated with high accuracy.

  Thereby, even if the navigation apparatus 1 cannot recognize the accurate current position based on the position information PS, the highly accurate estimated position based on the GPS signal speed V and the corrected angular speed φc is displayed on the map of the display screen. The estimated position of the vehicle 100 can be visually recognized by the user.

(2-2) Speed Output Processing Procedure Next, with respect to the speed output processing procedure when the speed detection unit 21 calculates the speed V of the vehicle 100 and outputs it to the navigation unit 3, the same reference numerals are assigned to the corresponding parts in FIG. This will be described with reference to the attached flowchart of FIG.

  When the navigation device 20 is powered on, the arithmetic processing block 22 of the speed detection unit 21 starts the speed output processing procedure RT2 and proceeds to step SP1. In this speed output processing procedure RT2, steps SP1, SP2, SP3, SP4, subroutines SRT1, SRT2, and SRT3 are the same as those in the case of the speed output processing procedure RT1 (FIG. 4), and thus description thereof is omitted. .

  After completing the subroutine SRT2, the arithmetic processing block 22 proceeds to the next step SP31. In step SP31, the arithmetic processing block 22 uses the height change amount Dh calculated according to the equation (8) and the movement distance Dm obtained based on the speed V calculated according to the equation (7). Sin θ is calculated according to the above, and based on this, cos θ is calculated according to the equation (17), and the process proceeds to the next step SP32.

  In step SP32, the arithmetic processing block 22 calculates a corrected angular velocity φc obtained by correcting the angular velocity φ according to the equation (18), and proceeds to the next step SP33.

  On the other hand, the arithmetic processing block 22 moves to the next step SP33 after completing the subroutine SRT1.

  In step SP33, the arithmetic processing block 22 sends the velocity V and the corrected angular velocity φc to the navigation unit 3, and proceeds to the next step SP6.

  In step SP6, as in the case of the speed output processing procedure RT1 (FIG. 4), the arithmetic processing block 10 waits until the measurement time mt elapses, and then returns to step SP1 and repeats a series of processing.

(2-3) Operation and Effect In the above configuration, the speed detection unit 21 can receive the GPS signal by the GPS antenna 6 as in the case of the speed detection unit 2 in the first embodiment. The offset acceleration αo is calculated by substituting the actual detected acceleration αGr, the vehicle acceleration αP, the altitude change amount Dh, the distance Dm, and the gravitational acceleration g.

  Therefore, as in the case of the speed detection unit 2, when the speed detection unit 21 can acquire the position information PS from the GPS processing unit 4, the vehicle acceleration based on the actual detection acceleration αGr actually obtained from the acceleration sensor 11 and the position information PS. By using altitude change amount Dh and gravity acceleration g based on αP, distance Dm, and atmospheric pressure PR, offset acceleration αo can be calculated with high accuracy.

  Further, when the position information PS cannot be acquired from the GPS processing unit 4, the speed detection unit 21 calculates the speed V without being affected by the gradient angle θ according to the equation (7), and sets the gradient angle θ according to the equation (18). Accordingly, by correcting the angular velocity φ to the corrected angular velocity φc, an error caused by the gradient angle θ can be removed.

  At this time, since the speed detection unit 21 can update the offset acceleration αo at any time, the position information PS cannot be acquired from the GPS processing unit 4 by suddenly entering the tunnel or hiding behind the building while the vehicle 100 is traveling. Even in such a case, by using the velocity V calculated based on the latest offset acceleration αo and the corrected angular velocity φc, highly accurate dead reckoning (dead reckoning navigation) can be realized.

  According to the above configuration, the speed detection unit 21 can obtain the actual detection actually obtained from the acceleration sensor 11 according to the equation (15) when the position information PS can be acquired from the GPS processing unit 4 as in the speed detection unit 2. By using the acceleration αGr, the vehicle acceleration αP based on the position information PS, the distance Dm, the altitude change Dh based on the atmospheric pressure PR, and the gravitational acceleration g, the offset acceleration αo can be calculated with high accuracy, and the offset acceleration αo The acceleration detection signal SA can be converted to the detected acceleration αG with high accuracy based on the zero gravity offset value Vzgo obtained by converting.

(3) Other Embodiments In the above-described embodiment, the case where the vehicle acceleration αP is calculated based on the position information PS supplied from the GPS processing unit 4 has been described. For example, a vehicle speed pulse signal composed of a pulse signal having a period corresponding to the speed may be acquired from the vehicle 100, and the vehicle acceleration αP may be calculated based on the vehicle speed pulse signal.

  In the above-described embodiment, the case where the stop state of the vehicle 100 is determined based on the variance Vvar of the speed V has been described. However, the present invention is not limited to this, and for example, the variance φvar of the angular velocity φ is calculated. Then, the stop state of the vehicle 100 may be determined based on the variance φvar.

  Further, in the above-described embodiment, the case where the offset acceleration α0 is calculated using the detected acceleration αG0 at time t0 in step SP15 of the offset acceleration calculation subroutine SRT1 (FIG. 5) has been described. For example, the offset acceleration α0 may be calculated by using, for example, the detected acceleration αG1 at the time t1 or using the average value of the detected acceleration αG0 and the detected acceleration αG1.

  Further, in the above-described embodiment, the case where the altitude change amount Dh is calculated based on the change amount of the ambient pressure PR has been described. However, the present invention is not limited to this, and for example, acceleration in the vertical direction is detected. It is also possible to provide a vertical acceleration sensor that converts the detected value by the vertical acceleration sensor into an altitude change amount.

  Further, in the above-described embodiment, the case where the pressure PR is converted to the height h according to the pressure altitude correspondence table TBL stored in advance in the storage unit 18 has been described. However, the present invention is not limited to this. formula

Accordingly, the altitude h may be calculated based on the atmospheric pressure PR. Here, t _Z is the temperature at an altitude h = 0 [m], and PR _Z represents the atmospheric pressure at an altitude h = 0 [m].

  Thereby, although the amount of calculation processing increases, the calculation accuracy of the altitude h can be improved.

  Further, in this case, as shown in FIG. 11 in which the equation (19) is graphed, the characteristic curve Q can be approximated as an approximate straight line AL in the portion AR having a relatively low altitude. If the altitude is known to be relatively low, the following formula represents the approximate straight line AL

Accordingly, the altitude change amount Dh may be calculated approximately. Thereby, the arithmetic processing in the arithmetic processing blocks 10 and 22 can be simplified as compared with the case of performing the arithmetic operation of the equation (19).

  Further, in the above-described embodiment, when it is determined that equation (9) is not satisfied and the altitude change amount Dh is affected by the non-altitude factor, the corrected altitude change amount Dhc calculated by equation (10) is used. However, the present invention is not limited to this. For example, the previous altitude change amount Dh is used as it is as the new altitude change amount Dh, or the previous altitude change amount Dh. Based on the change amount Dh and the previous height change amount Dh, a predicted value of the current height change amount Dh is calculated and used as a new height change amount Dh. It may be calculated.

  Furthermore, in the above-described embodiment, whether or not the altitude change amount Dh calculated by the equation (8) is influenced by a non-altitude factor is determined by the equation (9) using the maximum gradient angle θmax. Although the present invention is not limited to this, for example, the maximum altitude change amount Dhmax is defined as the maximum value that the altitude change amount Dh can take, and the absolute value of the altitude change amount Dh and the maximum altitude change amount Dhmax are defined. Whether or not the altitude change amount Dh is affected by a non-altitude factor may be determined based on the comparison result.

  If it is determined that the altitude change amount Dh is affected by a non-altitude factor, the maximum altitude change amount Dhmax is set as the new altitude change amount Dh, and the subsequent processing may be performed.

  Further, the gradient change rate λ is defined as the change amount of the gradient angle θ per unit time, and it is determined whether or not the altitude change amount Dh is affected by a non-altitude factor using the gradient change rate λ. May be.

  For example, the maximum gradient change rate λmax is set as the maximum value that the gradient change rate λ can take when the vehicle 100 is traveling normally. The speed detection unit 2 is obtained from the relationship shown in FIG.

Is used to calculate the immediately preceding gradient angle θ0 using the altitude change amount Dh and the distance Dm at the immediately preceding time t0.

It may be determined whether or not the altitude change amount Dh is influenced by a non-altitude factor based on whether or not both hold.

  Here, when it is determined that the expression (22a) or (22b) is not satisfied and the altitude change amount Dh is affected by a non-altitude factor, the following expression

Accordingly, the corrected altitude change amount Dhc2 may be calculated and used as a new altitude change amount Dh.

  Further, it is determined whether or not the altitude change amount Dh is affected by a non-altitude factor using an acceleration component (so-called longitudinal G, hereinafter referred to as longitudinal acceleration αv) applied in the longitudinal direction of the vehicle 100. Anyway.

  According to the general law of physics, between the longitudinal acceleration αv and the gradient change rate λ

The relationship is established. Therefore, the maximum vertical acceleration αvmax is set as the maximum value that the vertical acceleration αv can take during normal travel of the vehicle 100, and the following is obtained by applying the equation (24) to the equation (22) in the speed detection unit 2. formula

It may be determined whether or not the altitude change amount Dh is influenced by a non-altitude factor based on whether or not both hold.

  Here, when it is determined that the expression (25a) or (25b) is not satisfied and the altitude change amount Dh is affected by a non-altitude factor, the following expression

Accordingly, the corrected altitude change amount Dhc3 may be calculated and used as a new altitude change amount Dh.

  Furthermore, in the above-described embodiment, the case where the position signal PS is generated by the GPS processing unit 4 based on the GPS signal received by the GPS antenna 6 has been described. Various satellite positioning systems such as zenith satellite system, GLONASS (Global Navigation Satellite System) and Galileo (GALILEO) are used to receive the respective positioning signals, perform the positioning process, and generate the position signal PS. Also good.

  Further, in the above-described embodiment, the case where the present invention is applied to the navigation devices 1 and 20 mounted on the vehicle 100 has been described. However, the present invention is not limited to this, and for example, a portable navigation device, GPS reception, and the like. The present invention may be applied to various electronic devices that realize a navigation function without using a vehicle speed pulse signal or a similar signal such as a PDA having a function, a mobile phone, a personal computer, or the like. In this case, the electronic device is not limited to the vehicle 100 and may be mounted on a ship, an aircraft, or the like, or may be used alone.

  Furthermore, in the above-described embodiment, the acceleration sensor 11 as the acceleration sensor, the calculation processing block 10 as the detection acceleration calculation unit, and the offset calculation unit 18 as the offset calculation unit serve as an offset detection device for the acceleration sensor. Although the case where the speed detection units 2 and 21 are configured has been described, the present invention is not limited thereto, and the acceleration sensor offset is determined by an acceleration sensor having various other circuit configurations, a scheduled detection acceleration calculation unit, and an offset calculation unit. You may make it comprise a detection apparatus.

  The present invention can also be used in various navigation devices having an acceleration sensor.

It is a block diagram which shows the circuit structure of the navigation apparatus by 1st Embodiment. It is an approximate line figure used for explanation of a calculation principle of an altitude change amount. It is a basic diagram with which it uses for description of the fluctuation | variation of zero gravity offset, and the update of conversion reference potential. It is a flowchart which shows the speed output process sequence by 1st Embodiment. It is a flowchart which shows an offset acceleration calculation process procedure. It is a flowchart which shows an altitude variation correction process procedure. It is a flowchart which shows a speed calculation process procedure. It is a block diagram which shows the circuit structure of the navigation apparatus by 2nd Embodiment. It is an approximate line figure used for explanation of amendment of angular velocity. It is a flowchart which shows the speed output process sequence by 2nd Embodiment. It is a basic diagram which shows the relationship between atmospheric pressure and altitude.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,20 ... Navigation apparatus, 2, 21 ... Speed detection unit, 3 ... Navigation unit, 4 ... GPS processing part, 10, 22 ... Arithmetic processing block, 11 ... Acceleration sensor, 12 ... Barometric pressure sensor , 13 ... Yaw rate sensor, 15 ... Altitude change calculation unit, 16 ... Stop determination unit, 17 ... Speed calculation unit, 19 ... Storage unit, V ... Speed, αG ... Detected acceleration, αP ... Vehicle acceleration, gf: gravity acceleration component, Dh: altitude change, Dm: distance, mt: measurement time.

Claims (10)

An acceleration sensor that acquires an actual detection acceleration corresponding to a result of adding an offset variation to an acceleration in a traveling direction of a predetermined moving body;
A predetermined detection acceleration calculating means for calculating a predetermined detection acceleration that the acceleration sensor should inherently detect correctly;
Offset calculating means for calculating the amount of offset fluctuation in which the actual detected acceleration varies from the detected acceleration based on the difference between the actual detected acceleration and the scheduled detection acceleration. An acceleration sensor offset detection device. The above-mentioned detection acceleration calculation means is
2. The detection-target acceleration is calculated by calculating and adding a moving body acceleration representing the acceleration of the moving body and a traveling direction component of a gravitational acceleration acting on the moving body, respectively. The offset detection apparatus of the acceleration sensor as described in 2. An atmospheric pressure sensor for detecting atmospheric pressure;
A moving distance calculating means for calculating a moving distance of the moving body in a predetermined measurement period;
With
The above-mentioned detection acceleration calculation means is
Based on the atmospheric pressure detected by the atmospheric pressure sensor, the altitude change amount of the moving body in the measurement period is calculated, and the traveling direction of the gravitational acceleration is calculated using the ratio of the moving distance to the altitude change amount and the gravitational acceleration constant. The component is calculated. The acceleration sensor offset detection apparatus according to claim 2. The above-mentioned detection acceleration calculation means is
The acceleration sensor offset detection device according to claim 3, wherein when the altitude change amount is not within a predetermined altitude change range, the altitude change amount is corrected to be within the altitude change range. The above-mentioned detection acceleration calculation means is
The determination as to whether or not the altitude change amount is within the altitude change range based on a maximum gradient angle that is a maximum value of the gradient angle obtained from the altitude change amount. Offset detection device for acceleration sensor. The above-mentioned detection acceleration calculation means is
It is determined whether the altitude change amount is within the altitude change range based on the maximum gradient change rate that is the maximum value of the gradient change rate per unit time of the gradient angle obtained from the altitude change amount. The apparatus for detecting an offset of an acceleration sensor according to claim 3. The moving distance calculation means is
The apparatus for detecting an offset of an acceleration sensor according to claim 2, wherein the moving distance is calculated using position information or velocity information acquired by a predetermined satellite positioning signal receiving positioning means. A detected acceleration acquisition step of acquiring an actual detected acceleration corresponding to a result obtained by adding an offset variation to an acceleration in a traveling direction of a predetermined moving body by an acceleration sensor;
A planned detection acceleration calculating step for calculating a predetermined detection acceleration that the acceleration sensor should detect accurately;
And an offset calculating step for calculating the offset fluctuation amount in which the actual detected acceleration varies from the planned detected acceleration based on the difference between the actual detected acceleration and the planned detected acceleration. Acceleration sensor offset detection method. For the acceleration sensor offset detector,
A detected acceleration acquisition step of acquiring an actual detected acceleration corresponding to a result obtained by adding an offset variation to an acceleration in a traveling direction of a predetermined moving body by an acceleration sensor;
A scheduled detection acceleration calculation step for calculating a scheduled detection acceleration that the acceleration sensor should originally detect correctly;
An offset calculating step for calculating the offset fluctuation amount in which the actual detected acceleration fluctuates from the detected planned acceleration based on the difference between the actual detected acceleration and the planned detected acceleration, based on the characteristics of the acceleration sensor. Acceleration sensor offset detection program. Current position calculating means for receiving a positioning signal from a predetermined satellite positioning system and calculating a current position of a predetermined moving body;
An acceleration sensor that acquires an actual detection acceleration corresponding to a result of adding an offset variation to an acceleration in a traveling direction of a predetermined moving body;
A predetermined detection acceleration calculating means for calculating a predetermined detection acceleration that the acceleration sensor should inherently detect correctly;
Based on the difference between the actual detected acceleration and the scheduled detection acceleration, an offset calculating means for calculating the offset fluctuation amount in which the actual detected acceleration varies from the detected scheduled acceleration due to the characteristics of the acceleration sensor;
Information presenting means for calculating the acceleration using the offset fluctuation calculated by the offset calculating means, and presenting information on the position of the moving body based on the speed of the moving body calculated using the acceleration; A navigation device characterized by comprising:

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